A concussed serenity sets in somewhere in the middle of the ceaseless ballet of metal and machismo in Michael Bay’s “Transformers: The Last Knight.” Freed of concerns like plausibility or story, you can simply gape in wonder at the ruthlessly thunderous images in front of you.

Maybe that’s the feeling of brain cells dying a painful, anguished death. It’s a sensation I imagine cornered boxers sometimes experience while blow after blow rains down upon them. Dazed by the unrelenting digital demolition on screen, thoughts go through your head like: ‘Can this movie literally crush me?’ ‘Is death by Dolby possible?’ and ‘You know, it’s really time to get the car washed.’

By the time you’ve scraped yourself off the floor after all 149 minutes of the 3-D “The Last Knight,” you feel the need to compensate for the sheer gluttony of destruction, of unrelenting bigness. Maybe fast for a little while, you think, or just sit quietly in a corner. Bay might be spinning another tale of Autobot v. Decepticon in which the fate of the planet hangs in the balance, but his real battle is conquering you, the moviegoer. And make no mistake about it. He’s gonna win.

“Transformers: The Last Knight, is, if nothing else, a pummeling. The fifth in the franchise and second in the “Wahlberg Years” (Mark Wahlberg replaced Shia LaBeouf as lead in the last installment), “The Last Knight” continues the Hasbro toy adaptations and expands further into the alien machines’ mythology.

The script by Art Marcum, Matt Holloway and Ken Nolan ropes in a backstory involving Arthurian legend, suggesting the magic of Merlin was nothing but Transformer technology. Centuries later, the continual arrival of Transformers on Earth connects to these ancient events. There are crucial objects — Merlin’s staff, a talisman that attaches itself to Wahlberg’s Autobot-defending Cade Yeager — that bring constantly arriving Transformers, plummeting in space ships from the sky, and eventually, the vengeful leader of their home planet, Cybertron.

With Optimus Prime away on holiday (or searching for something or other back on Cyberton), the human population has turned against the Transformers. One can see why. They’re swaggering, bickering bags of bolts who eschew their best parlour trick (transforming into cars and trucks) for avalanches of ammo. There is, for a moment, a touch of metaphor for immigrant empathy in their unfortunate status, but it quickly gets buried in the mounting debris.

That is, at any rate, what I could make out. Stonehenge has something to do with the plot, too, as does Anthony Hopkins, who plays the latest in a long line of guardians to these mysteries. There’s also an Oxford scholar (Laura Haddock) skeptical of Round Table legend, and, briefly, an elite scientist (Tony Hale) whose insistence on solving intergalactic problems with silly things like physics is, here, a joke. “Transformers” is like the anti-“Martian”: brawn over brains.

“This here’s a big boy zone,” announces the Autobot commando Hound (John Goodman) in a junkyard. But he might as well be providing the movie’s ethos.

Later there’s a submarine chase and a planetary battle in the air as “The Last Knight” — an exercise in enormity — insatiably hurtles toward feats of greater and greater grandiosity. It’s an empty pursuit; there’s no explosion big enough to give Bay the fix he needs.

But what makes the “Transformers” movies different from other blockbuster colossuses is Bay. Whatever his deficiencies in other areas (coherence, emotions, women), he remains the most proficient master of big-screen rock ’em sock ’em mayhem. His manipulation of scale is unsurpassed, as is his ability to synthesize obscene amounts of visual effects into an astonishingly fluid choreography of colour and chaos.

After two and half hours of pulverizing action, there’s nothing to do but raise the white flag, admit defeat, and shudder as you pass the theatre for the latest “Cars” movie. No more, please.

“Transformers: The Last Knight,” a Paramount Pictures release, is rated PG-13 by the Motion Picture Association of America for “intense sequences of sci-fi action violence, brief sexual humour and language.” Running time: 149 minutes. Two stars out of four.